Benadryl, Sleep Aids, Similar Drugs, May Increase Dementia Risk: Study

The active pharmaceutical ingredient found in Benadryl and a number of sleep aids may be linked to an increased risk of dementia, according to the findings of new research. 

In a study published in the JAMA Internal Medicine on January 26, researchers from the University of Washington School of Pharmacy indicate that a class of drugs that cause anticholinergic effects may cause permanent cognitive impairment among some users.

The class of drugs include Benadryl, some antidepressants and several over-the-counter sleep aids.

The research involved data from 3,434 participants ages 65 or older, who had no dementia when the study began. Researchers followed up with participants every two years, from 2004 through September 2012.

According to the findings, the most common anticholinergics used by the subjects were tricyclic antidepressants, like Sinequan, first-generation antihistamines, like Benadryl and Chlor-Trimeton, and bladder antimuscarinics, such as Ditropan.

About 23% of the subjects developed dementia, and most of those that did were also diagnosed with Alzheimer’s disease. They found that the higher the cumulative use of anticholinergics, the higher the risk for dementia and Alzheimer’s. with those taking the highest total standardized daily doses facing a 54% increased risk of dementia.

“Older adults should be aware that many medications — including some available without a prescription, such as over-the-counter sleep aids — have strong anticholinergic effects,” Dr. Shelly Gray, the lead study author, said in a press release issued by the university. “And they should tell their health care providers about all their over-the-counter use.”

The study was originally designed to investigate claims that cognitive effects by such drugs were temporary, but instead found an increased risk of permanent cognitive damage. However, Gray cautioned that patients should not stop taking any prescribed therapy without first consulting their doctor.

“If providers need to prescribe a medication with anticholinergic effects because it is the best therapy for their patient, they should use the lowest effective dose, monitor the therapy regularly to ensure that it’s working, and stop the therapy if it’s ineffective,” Gray said.